In prior art business communication switching systems (also referred to as PBXs), a conference call can be set up between a plurality of station sets by a station set conferencing other station sets into a conference. Indeed, it is possible to have two conferences set up between two different sets of station sets and to join those two conferences. A station set on the first conference conferences a station set on the second conference into the first conference, which results in all of the station sets of the second conference becoming par of the first conference. The problem that arises is that the two sets of station sets cannot be disengaged from the resulting conference call without each station set hanging up, since no station set has control of the resulting conference. In prior art business communication systems, conference calls result in many awkward and inefficient situations because one station set does not control the conference.
Within the AT&T long distance telephone network, a teleconferencing service known as the Alliance Dedicated Teleconferencing Service is available. An Alliance system comprises a teleconferencing bridge connected to a 4ESS toll switch. The Alliance system can conference up to 56 telephone lines interconnected via the 4ESS toll switch to the teleconferencing bridge. Conference calls arc setup and controlled by AT&T operators who can selectively add and drop people to a conference and who can obtain a visual display of the individuals on the conference by name and telephone number.
In an attempt to improve upon the Alliance system, U.S. Pat. No. 4,796,293 discloses interposing a service computer between a coordinator of a conference and the Alliance system. The service computer uses the same interface into the Alliance system as that of an operator terminal inter The service computer gives the coordinator an improved human interface to the Alliance system than that of an AT&T operator terminal. The service computer takes the place of the AT&T attendant. In order to establish communication with the service computer, the coordinator is required to use a separate packet data system to establish communication between the service computer and the coordinator's computer terminal. Once this communication has bcen established, the coordinator has the same capabilities as the AT&T operator. The service computer assumes that the first terminal to establish communications with the service computer is the coordinator's terminal. Other conferees can interconnect their computer terminals to the service computer via the packet network if each has a login ID and a password. Each conferee who accesses the service computer via their own computer terminal also has displayed for them the names and, telephone numbers of the people on the conference. The coordinator has the capability to sub-conferences. All conferees converse using regular telephones. Once subdivided, the coordinator can also recombine the two sub-conferences.
The problems of the prior art are the lack of control and identification in business communication switching systems and the need in the system disclosed by U.S. Pat. No. 4,796,293 for a separate service computer which requires interconnection via a separate packet network. Further, in the case of U.S. Pat. No. 4,796,293 the conference call must begin on a dedicated conference bridge. What is needed is a unified conferencing system whereby users can, during the course of a two party conversation, convert that two party conversation into a conference call with the originator of the conference call controlling the conference call with respect to adding and dropping individuals. Further, each user has displayed for them the participants in the conference calls on the telephone terminal of the user.